Elevated Levels of Plasma Immunoassayable Aldosterone in a Mild Form of 17 Alpha-Hydroxylase/17,20-lyase Deficiency Diagnosed at the Age of 50

Objective: 17 Alpha-hydroxylase/17,20-lyase deficiency (17OHD) is a form of congenital adrenal hyperplasia caused by homozygous or compound heterozygous mutations in the CYP17A1 gene. Impaired activities of 17 alpha-hydroxylase and 17,20-lyase typically induce hypertension, hypokalemia, and amenorrhea, with the vast majority of patients with 17OHD are diagnosed in adolescence. Methods: We present a case of 17OHD diagnosed at the age of 50 with complete endocrinologic investigations and genetic analysis. Results: The patient had hypokalemia and a low cortisol level. Her dehydroepiandrosterone sulfate (DHEA-S) and androstenedione levels were undetectable, although her adrenocorticotropic hormone (ACTH) level was elevated. She had markedly elevated pregnenolone, progesterone, deoxycorticosterone, and corticosterone levels. In addition, her plasma renin activity and plasma aldosterone concentration were suppressed and elevated, respectively. Rapid ACTH stimulation increased the hormones upstream of 17 alpha-hydroxylase, and overnight 1-mg dexamethasone suppressed them. The patient was thus diagnosed with 17OHD. Genetic testing confirmed the diagnosis, revealing 2 distinct mutations in the CYP17A1 gene, c985_987delTACinsAA and R416C, which have been previously reported. Conclusion: The present case is a mild form of 17OHD that had gone undiagnosed until the age of 50. The R416C genotype seems to relate to a mild phenotype. Mild 17OHD may remain undiagnosed or be misdiagnosed as primary aldosteronism or idiopathic hyperaldosteronism. Abbreviations: ACTH adrenocorticotropic hormone 17OHD 17 alpha-hydroxylase/17,20-lyase deficiency Ms metabolites PAC plasma aldosterone concentration DHEA-S dehydroepiandrosterone sulfate